(1) Field of the Invention
The present invention relates to a manufacturing method for a compound semiconductor device, in particular to a manufacturing method for a compound semiconductor device, the method including a surface-cleaning process after a resist pattern is removed.
(2) Description of the Related Art
Generally speaking, in a lithography process of a manufacturing process for a semiconductor device, a resist pattern is formed on a semiconductor layer, the semiconductor layer is etched using the resist pattern, and the resist pattern is removed using a remover and the like.
In the lithography process, if organic substances such as resist still remain on the semiconductor layer after the resist pattern is removed, these remaining substances result in a film removal and the like. It is possible to cause a problem in terms of credibility. Accordingly, in order to remove remaining organic substances, an O2 plasma etching is performed on the semiconductor layer after the resist is removed (e.g. refer to Ralph E. Williams. “Gallium Arsenide Processing Techniques” (United States), ARTECH HOUSE, INC., 1984). In addition, according to technology disclosed in Japanese Laid-Open Patent Publication application No. 2001-185520, remaining organic substances made of Si on a semiconductor layer are removed by combining ozonized gas, ozonized water and hydrogenated water.
Additionally, in a case where the semiconductor layer is a compound semiconductor layer made of GaAs and the like instead of Si, a desired device characteristic of the compound semiconductor device cannot be obtained when remaining organic substances are removed by O2 plasma etching during a lithography process of the compound semiconductor device having such compound semiconductor layer. That is, the compound semiconductor layer is damaged when the O2 plasma ashing is performed on the semiconductor layer in a state where the compound semiconductor layer is exposed after removal of a resist pattern.
Here, removal of organic substances remaining on a compound semiconductor layer not by O2 plasma ashing but by ozonized gas, ozonized water and hydrogenated water had not been practiced under a consideration of a strong oxidization capability of the ozonized gas, the ozonized water and the hydrogenated water.